Self-assembled chitosan/heparin multilayer film as a novel template for in situ synthesis of silver nanoparticles.

Chitosan and heparin multilayer films were successfully constructed via layer-by-layer self assembly. These films were used as a polymeric template to synthesize silver nanoparticles. The silver concentration and nanoparticle size can be simply controlled by the assembly pH and loading pH, as demonstrated by UV-visible spectroscopy, transmission electron microscopy and atomic absorbance spectroscopy. The pH tunable uncompensated charge density within the multilayer films is believed to have great effect on the loading of silver ions, and then control the size and amount of silver nanoparticles within multilayer films. The antibacterial experiment shows that the silver nanoparticle-loaded chitosan/heparin multilayer films exhibit greatly enhanced antibacterial performance compared to the chitosan/heparin multilayer films without silver nanoparticles. In addition, the strong antibacterial property of silver nanoparticle-loaded films can last more than 1 month. Our method of in situ synthesis of metal nanoparticles in biocompatible multilayer films might provide great potential to design biofunctional nanocomposite films.